Engine

Learn the database engine with create_engine.

Engine

create_engine sets up SQLAlchemy's database connection. It takes a connection string and returns an Engine object. For an in-memory SQLite database, use sqlite:///:memory:.

from sqlalchemy import create_engine

engine = create_engine("sqlite:///:memory:")
print(engine.url)

The Engine manages the connection pool; actual queries go through a Session. You create the Engine once in an application.

Connection string

The connection string specifies the database type and location. For SQLite, the form sqlite:///path is used; :memory: means an in-memory database.

# In-memory
engine = create_engine("sqlite:///:memory:")
# File-based
engine = create_engine("sqlite:///uyeler.db")

For other databases, a string like postgresql://user:pass@host/db is used. SQLAlchemy picks the right driver from the string.

Exercise Create Engine and print

Start with from sqlalchemy import create_engine. Define an engine with create_engine("sqlite:///:memory:"). Print the connection string with print(engine.url).

Show example solution

from sqlalchemy import create_engine

engine = create_engine("sqlite:///:memory:")
print(engine.url)

Test yourself

What parameter does create_engine use to connect?
- A file object
- A connection string
- A class name
- A user name
Show answer

A connection string — create_engine takes a connection string to connect to the database.

Complete the create_engine call

from sqlalchemy import create_engine

engine = create_engine("____")

Show answer

from sqlalchemy import create_engine

engine = create_engine("sqlite:///:memory:")

Match the Engine concepts

create_engine

Creates the engine
engine.url

Gives the connection string
sqlite:///:memory:

In-memory database
Engine

Manages the pool

Next lesson: Session

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